1. Field of the Invention
The invention relates to a bicycle frame, more particularly to a steering bearing assembly for connecting a front wheel and handle bars to the bicycle frame.
2. Description of the Related Art
FIGS. 1 to 4, illustrate a steering bearing assembly of a bicycle frame according to U.S. Pat. No. 5,095,770 which is used to connect a front wheel and handle bars to the bicycle frame. The steering bearing assembly includes a steerer tube 33, one end of which is connected to a fork 31 that carries the front wheel 13, a head tube 21 that is connected fixedly to a top tube 19 and a down tube 23 of the bicycle, and a stem 37 that carries the hand bars 15.
The steerer tube 33 extends through the head tube 21 and through a connector 35 of the stem 37. In order for the steerer tube 33 to rotate relative to the head tube 21, a lower bearing assembly 47 and an upper bearing assembly 49 are mounted between the steerer tube 33 and the head tube 21. The upper bearing assembly 49 is located at an upper end of the head tube 21 and includes a first race 57 and a second race 59 which encase cooperatively a plurality of ball bearings 61. The first and second races 57, 59 are supported to rotate relative to each other by the ball bearings 61. The first race 57 is fixedly connected with the head tube 21 so that it rotates with the same. The second race 59 has an inner diameter that is greater than an outer diameter of the steerer tube 33 so that the steerer tube 33 is carried by the upper bearing assembly 49 with a clearance formed between the second race 59 and the steerer tube 33. The second race 59 has an annular contact face 63 which tapers at an angle with respect to a longitudinal axis 65 of the steerer tube 33.
An annular compression ring 67 with a gap 69 is disposed above the second race 59 of the bearing assembly 49. The compression ring 67 has an upper surface 71 and a tapered contact surface 75 which matches the contact face 63 of the second race 59 in the bearing assembly 49.
When all of the elements are in place, an adjuster nut 79 is threaded to an internally threaded upper end 77 of the steerer tube 33. At this stage, a head 83 of the adjuster nut 79 contacts an upper end of the connector 35 and forces the latter downward on the steerer tube 33. Longitudinal and radial forces are exerted consequently on the compression ring 67 such that the latter is compressed against the steerer tube 33 and the second race of the bearing assembly 49, thereby locking the compression ring 67 in place on the steerer tube 33.
The above-mentioned steering bearing assembly is advantageous in many aspects. However, it still has a drawback. The internal thread at the upper end of the steerer tube 33 can wear out due to constant vibration of the bicycle when in operation or due to a long period of use. When replacing the steerer tue 33, the user has to disassemble all the connecting parts, such as the stem, the head tube or the like, thus inconveniencing the user.